This invention relates to the process of removing mercury from water. Mercury is a toxic element, and if water is contaminated with it, standard water treatment processes used by public utilities are not effective for removal and levels become a problem if disposal is continued over a period of time.
The State of Tennessee limits the levels of mercury in drinking water to not more than two parts per billion. Levels of mercury in water discharged from treatment processes are negotiated but levels of two or less parts per billion are usually required. Methods were known for removal of mercury in waste water in the parts per million range, however, there are few known methods for purification to two parts per billion.
Previous studies have provided a method for removal of mercury from aqueous solutions by reacting the mercury with ferrous sulfide to produce mercuric sulfide; however, the level of mercury was still greater than two parts per billion. Use of materials such as cadmium, lead, silver and chromium sulfides is unsatisfactory because discharge of fluids containing these materials is severely restricted by statute.
Ion exchange resins specifically formulated for removing mercury from water were tried. Using procedures recommended by the manufacturer, attempts were made to remove mercury from water; however, levels of two parts per billion could not be reached.
In light of the difficulties involved in these attempts to remove mercury to a level of two parts per billion in water, a process was developed and that process is the subject of this invention.